The thick shelled river mussel (Unio crassus) brings LIFE+ back to rivers

- As a RESTORE-partner?

DisturbancesNumerous Uc-populations have become extinct in Sweden, presumably due to large-scale anthropogenic disturbances, causing habitat degradation and fragmentation. Urbanization and fragmentation seems to be of particular importance, at least in the southern part of its distribution range (Fig 4).

Fig 1. Happy mussels = Healthy Rivers

The project have four major objectives: 1) Mapping host-fish utilization by the Uc to ensure successful conservation actions for both the Uc and the host-fish species. 2) Recreate natural river dynamics by restoring structures (ie substrate and cover) and processes (ie connectivity and corridor functions). 3) Re-introduction by stocking Uc-juveniles and glochidia-infected host-fish. 4) Information events to gain public awareness about the need of river restoration.

PCA1 (35%)

PC

A2

(23

%)

Catchment size

-2

-1

0

1

2

3

-2 -1 0 1 2

%Agriculture

%Urbanized Fragmentation

%Lakes

Fig 2. Unhappy mussels = Depressed Rivers

Here, we present the UC4LIFE-project which aim to strengthen the conservation status of the endangered thick shelled river mussel (Unio crassus, henceforth called Uc,) and improve the ecological riverine status within its distribution range. As being a key-stone species, actions beneficial for the Uc will positively impact water quality, biodiversity, including other endangered species, such as Atlantic salmon, bullhead, freshwater pearl mussel and otter.

4.9 M€ The objectives

The County Boards, Karlstad University, and The Nybroå Water Council/Högestad & Christenehofs Förvaltning, Sweden1 2 3

= Extinct Uc-populations = Uc-populations still present

The actions

Fig 4. PCA revealed that extinct Uc-populations were associated with a high degree of urbanization and in-river fragmentation, whereas Uc-populations still present were associated with larger catchment areas, more lakes and less agriculture and urbanization in the catchment areas.

The distribution rangeThe Uc has a fragmented (totally c 100 sites) and narrow south-eastern distribution in Scandinavia (Fig 3). Reproduction is low or failing in most of the remaining populations. The Uc is threatened (EN) and constitutes a major conservation concern in Sweden as well as in Europe.

Fig 3. Inset A shows the main historical Uc-distribution range (shaded area) in Scandinavia. Inset B shows the location of the 12 project-sites (marked red), including the catchment areas (areas marked light-green), where river restoration actions are planned for.

Alongside the habitat oriented actions, we aim to build up public knowledge and awareness about the importance of river restoration and management by using Unio crassus as the “pedagogue”. For example, information campaigns and field trips with “hands-on activities” for local school kids and families will be conducted as part of the project.

The central goal is that experiences obtained from this project will have positive long-term effects, functioning as a catalyst initiating additional river restoration projects worldwide. Thus, the UC4LIFE-project will not be silent as a mussel!

The Unio crassus constitute the main “flag-ship species” for river restoration actions at 12 project sites, covering c 40 000 ha. Major actions include host-fish mapping at the project sites, re-meandering measures at two sites (five km), removal of eight migration obstacles and re-introduction of Uc at the sites where it has become extinct.

Check us up @

UCFORLIFE.SE

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1 1 2 1 3Ivan C Olsson , Jakob Bergengren , Martin Österling , Vibeke Lirås , Charlotte Lindström and Ulrika Svärd